


Krypto-Bat Twins AU

by SilverWhiteRaven



Series: Krypto-Marinette AUs [3]
Category: Batman - All Media Types, DCU, Maribat - Fandom, Miraculous Ladybug, Superman - All Media Types
Genre: Adopted Marinette Dupain-Cheng | Ladybug, Gen, Krypto-Bat AU, Kryptonian AU, MLB/DC Crossover, MariBat, Marinette Wayne, Marinette and Clark are Twins, Marinette is Batman, Marinette is Kryptonian, Marinette is Robin, Mominette, twins au
Language: English
Status: In-Progress
Published: 2020-04-16
Updated: 2020-04-16
Packaged: 2021-03-02 02:48:40
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,614
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23677912
Author URL: https://archiveofourown.org/users/SilverWhiteRaven/pseuds/SilverWhiteRaven
Summary: Headcanon List and Timeline for one of the Krypto-Mari AUs. Marinette is Clark's twin sister, and she is found and raised by Bruce Wayne, eventually becoming both Robin and Batman.
Series: Krypto-Marinette AUs [3]
Series URL: https://archiveofourown.org/series/1702447
Comments: 22
Kudos: 212





	Krypto-Bat Twins AU

**_Krypto-Bat_ **

  * Twins AU with Marinette and Clark, Aka, Kia Jor-El and Kal-El
  * They were sent from Krypton at the same time in separate pods/ships, and when they land on earth, the pods are separated enough to land in two different places
  * Kal-El is, as originally, ends up in Smallville, adopted by the Kents as Clark
  * Kia ends up in Gotham
  * Bruce is already an adult here, and already Batman, including having taken in Dick and potentially Jason as well
  * Batman is the one to find Kia, mostly because, ever-vigilant, he knows about when something is about to crash into the territory he protects and is determined to be the first to arrive before anyone else.
  * He takes her in because for one, ‘what the heck, a tiny child with super-strength is in my backyard’ and felt he lucked out with her not ending up in the hands of a villain instead. For two, he’s really curious about what she and her little partially-destroyed space pod are. For three, The Justice League hasn't been formed, it's not even a baby of a thought in Batman’s head yet, so he has no one else he trusts to be able to hand a super-powered alien baby off to, so, congrats, Bruce, you have a daughter!
  * Dick is like ‘oh heck yes, someone else to teach all the ways of being one bendy acrobat’
  * Also, Since Dick can’t get the Nightwing name from Superman (since there is no Superman yet) He has a different hero name, Blackbird
  * Jason is the dotting older brother type and none of you will change my mind
  * “Oh god the teething” will be something Bruce groans about in the future when talking about raising this child. First of all, she’s really strong, and develops her physical invulnerability early on, so you have this baby that will probably chew on the granite gargoyles around the mansion and all the batarangs in the cave
  * Kia, now named Marinette Wayne, spends a lot of her time with Alfred, so she learns early on how to seem like some all-knowing, all-wise entity, and how to control her emotions and outward expressions. They bats will learn to rightly fear her as much as they fear Alfred
  * Learning how to be a mini-Alfred doesn't stop her from being fun, being absolutely sweet, or even a sunshine child. Alfred made sure she doesn’t pent up or bottle emotions, she learns how to deal with them in a healthy way and divert the bad ones into powering good ones
  * Pair that Alfred attitude with training to control her powers and, eventually, training to defend herself as well as fight, in case she ever decides to join the ‘family business’, and you have a force to be reckoned with, even from a young age
  * The Jason dying thing can either happen or not
  * If it happens, when he comes back, his rage about being ‘replaced’ can be lessened, considering he already knew the Robin mantle wasn't meant to ever sit permanently on anyone’s shoulders
  * Hell, he even looked forward to the day Marinette would be offered the chance to take it up, he may actually rather be more peeved that it wasn't saved for her before someone else filled it in
  * A new hero name Jason may potentially take is Cardinal. He takes it up either because dying never happened, so he never becomes Red Hood after Robin, or, he eventually rejoins the family and decides to take up a new one after dropping the RH name. 
  * Damian coming around is going to be funny, here is why
  * Marinette and Damian would be about the same age at this point, so you have two ten year olds duking it out
  * One ten year old is trying to kill all the Robins
  * The other ten year old is trying to prevent the other ten year old from killing her brothers
  * Damian is a trained assassin that knew she had super strength because the LoA knows things it shouldn't, but they also don’t have knowledge of Kryptonite or her invulnerability, so he isn’t prepared at all for her interference
  * Marinette is a semi-trained not-yet-vigilante with super strength, invulnerability, and a determination to pin down her new brother and tell him to stop trying to kill their brothers
  * She utilizes a lot of her knowledge from Alfred and gains some well earned but reluctant respect and wariness from Damian
  * All her pinning of him, something she only manages to do out of pure strength because her fighting skills are not as fine and sharp as Damian’s yet, allows for her to continuously rant to him about morals, her explanations of why he shouldn't kill her brothers, and her thoughts on how terrible and inaccurate the teachings of the LoA are. He is forced to hear all of this, and, eventually, he actually listens
  * It helps that he also learns to stop attacking the other Wayne children because, with Marinette as their ever-vigilant protection and buffer, he has no hope of succeeding, so he might as well play nice
  * Damian still takes up the Robin mantle, Marinette letting him, as she has no desire for it yet
  * They’re both 15 when Damian decides to take off the Robin suit and, instead of continuing to pursue the Batman title as a ‘rightful heir’, wants to make his own name for himself
  * His new hero name is Starling
  * Marinette finally accepts the offer to be Robin
  * This is such bad news for the criminals, not going to lie, but so much fun for her, for the bats, and for us
  * First of all, the new costume
  * We all know about how the ‘traffic light’ might just be a way for Batman to be able to keep an eye on his kid while also making sure no one will hit them with their car when they run across the street like idiots without looking
  * But Marinette is invulnerable and also has enough fashion sense to demand she tine down the colors
  * She also has taken a liking to the idea of following in her dad’s footsteps and making her Robin look to be as dark, scary, and Cryptid-y as possible
  * So here is the suit:
  * The cape is black on the inside, the outside is an almost-black green that allows for blending into the foliage of all the ivy that grows all over the walls of the old buildings of the city
  * The eyes/lenses of her mask are gold/yellow instead of white, since it was the only place she was willing to add the color. It helped that it would create a creepy eye-glow effect
  * The body of the suit is black as well
  * The gloves and boots are a dark red, with an uneven fade into the black of her arms/legs. This causes an illusion of her having been walking through the blood of her enemies, while having also just removed her hands from the chest cavities of the last ones she dealt with. Obviously, she’s going for the scare-factor with that particular look, and Bruce is admittedly impressed with it, even if he disapproves of her making people think she doesn’t follow the no-kill rule
  * Over-all, the look is high-key intended to make her seem like a Cryptid, much like the Batman one is supposed to
  * Second! This is about the time all her other powers are going to be coming into the light
  * So Gotham and its criminals are introduced to a new Robin, and while it may seem nothing odd, they have another thing coming
  * Robin is suddenly creepy as hell, for one, especially with the dark and bloody appearance paired with the seemingly unnatural ability to be bendy and lithe
  * Robin is also much stronger, and a few of the smart ones decide never to engage her in combat.
  * Robin is also suddenly much faster than before, randomly at first, almost seeming to teleport. Rumor has it even Batman was shocked the first few times
  * Criminals started using insulated grips on their weapons because their weapons were getting unnaturally hot
  * Coats became common with the minions of villains, because hearing breathing from the shadows would sudden be accompanied by indoor breezes and temperature drops
  * Wait… is, is Robin, looming? Since when did Robin loom like that? When did they start being able to soundlessly move closer? Wait, hold on, since when did Robin’s feet not touch the ground??
  * They hate how suddenly they can't hide things, either, Robin seems to know where they hid all their weapons, their explosives, their traps, their plans, everything
  * Evil people start hoping really, really hard that the shadow they just saw move is Batman, and only Batman
  * You guys get the idea, Marinette as Robin is effective and scary and no one outside the Bat Clan/Family know how she does it
  * Clark, over in Smallville, is dealing with all these new powers, too, and our thoughts go out to him not having as great an outlet for them as Marinette does
  * But hey! He becomes Superman at, like, 22, so we can skip right to that! In just a moment!
  * [Interlude: Hawkmoth.]
  * It is purely by accident that Marinette, 16 years old and still freshly mantled, finds him and ends up taking him down. It was supposed to be a very casual family trip to Paris, nothing more, and it went rather sideways for her instead.
  * The Justice League still has yet to be formed, so asking for help was simply hit or miss with wherever Paris sent the plea. The Waynes didn’t even know one had been sent to Gotham while they were gone, aimed at Batman, until after the family returned.
  * The family got caught up in the middle of a joint Akuma and Sentiminster attack, Marinette the only one able to escape fast enough to change into Robin. She joins the Ladybug and Black Cat superheroes in fighting, her presence both shocking and relieving them
  * She learns about her vulnerability to magic during the fight. She can take the physical blows just fine, but the moment she’s struck by a magical blast, she feels it like any other person. She got lucky that it wasn't a terrible hit, or one with magical side-effects, but it did injure her, and painfully
  * The other heroes realize she needs more protection, and are able to offer her a Miraculous, which she accepts in an instant, not at all wanting to keep getting injured. After she transforms, the blasts no longer hurt her, and she can take the physical blows even better than she had before, not to mention she was loving the extra power-boosts on top of what she already had
  * No, using a Miraculous doesn’t hurt her or make her sick, because channeling or ‘wearing’ magic is different than being attacked with it (Plus, in DC canon, Superman is able to use magic items (it was a sword if I remember right) that can grant him powers and such. Having a vulnerability to something does not equal having a negative reaction to general contact with it. 
  * “Just because a knife can cut you doesn't mean you have to grasp it by the blade; grab the handle.” - SilverWhiteRaven)
  * Her X-Ray and 4-D vision powers start acting up, and this is where she purely by accident gets to see exactly where Hawkmoth and Mayura have hidden themselves while they wait the fight out. She does notice she can’t X-ray any of them while their Miraculous were transforming them, and she guessed it was another magic thing interfering with her abilities
  * As soon as the Sentimonster and Akuma are defeated, she informs the two local heroes about who she saw and where
  * They seemed uncertain, and a bit sad about the news, and guessed they may have had previously unknown personal connections to their villains
  * She helps them make a quick plan of action. They used the post-battle recovery time that usually happens, the short recharge period, to their advantage
  * The three of them storm the Agreste mansion together, and it’s all over before even a rush of adrenaline can kick in
  * Robin spends a short moment of time to monologue a rant on morality and heroism to the two defeated supervillains as their two abused Miraculous are recovered. She was pretty sure that by the time she finished her speech and left to rejoin her family, both heroes were looking at her like they had instant crushes
  * Ideas for the Justice League start up after learning about the hit-and-miss cries for help from Paris
  * [End Interlude: Alright, back to it!]
  * By 22, Marinette has gone through 7 years of being Robin, and also college, and she and Damian have joined Tim in running Wayne Enterprises. Tim can go take a nap now, and none of the other Waynes are going to let anything stop him
  * Marinette, the genius she is, has invested in Stuart Semple, the creator of Black 2.0, as her first move in the business, and that I will come back to in a minute
  * Superman reveals himself to the world, and, loandbehold, every member of the Bat Clan who are in on her secret recognizes that very power set he displays, and all eyes are on Marinette
  * She realizes, too, that suddenly, she isn't the only one. Her escape pod was too damaged and missing too many parts after crashing to have given her anything about her original home, and now there's Someone Else who might have answers!
  * Pulling herself together, she asks her dad to accompany her to Metropolis, all the way in Kansas (yes, I am doing that, it is way more logical to protect a whole country when the city you put yourself in is in the middle of the thing and not even over on the coast closest to Alaska and Hawaii)
  * Marinette, when she gets there, makes her way to the top of the tallest tower, Batman in tow as her overseer and moral/emotional support
  * She gets Superman’s attention by legit just yelling for him, because what else do you do from the top of buildings besides yell into the wind?
  * He shows up, a little confused, but mostly surprised by the sight of someone who looks a lot like him
  * She’s very nervous now, a bit scared that they're wrong and that Superman isn't like her, that they are nothing alike, and as she notices their similarity in appearance, is anxious about how high her hopes have suddenly become, and how far of a fall the disappointment will be. But a little reassurance from her dad in the shadows and she gets the words out
  * “Hi, I’m Marinette, and I was wondering- Well, I mean, I needed to know- Just- Wow this is hard, I’m not usually like this, uhm- Superman, are you- are we- did you come from the same place I did? Can you look at me, and- just x-ray me if you can do that, because I can, and if you can, too, that might mean… Well… Please..?”
  * His eyes are wide and disbelieving but he does it, he looks, and all the time that he, too, spent looking at himself with his X-ray and 4-D vision, comparing his biology and it’s differences to that of humans, recognizes the traits of a Kryptonian in her. “Kia?”
  * Marinette tears up at his response, and chokes out, “I don’t know if that’s me, but please, I want to find out.”
  * Marinette is able to collect herself, as is Superman, enough to call Batman out of the shadows and introduce the two, explaining that Batman had ‘assisted’ (have to at least try to keep secret identities intact) in her raising and was simply acting as backup and support for her while she came to Metropolis
  * Superman invites her to visit the Fortress of Solitude with him, and she accepts, telling her dad to head home and, if things went well, not to expect her home for a few weeks, as she would be spending all of her time learning everything she could
  * There’s a lot of happy crying and comfort hugs the moment the Fortress welcomes her as Kia Jor-El, twin of Kal-El
  * Just like she warned Bruce, she spends weeks away in the Fortress, learning as much about Krypton as she can get
  * She listened to the holograms of her birth parents telling her stories, even the ones every Kryptonian child was told to scare them into behaving, or little tales told to teach morals. She didn't care that she was already an adult, already knew all these lessons from human versions, but they were what she wanted to hear
  * Learning of old legends, gods, and mythical creatures were some of her favorites to hear, and she was determined to retell them to her family when she returned
  * She listened to a lot of kryptonian music, too, discovering it had just as much variety in genres and cultures as Earth
  * You can bet your bucks that she is going to be recreating Kryptonian instruments a to learn to use, as well as learn every dance the Fortress has recorded in its archives
  * She has a field day when she discovers there are kryptonian puzzle boxes she can recreate
  * Her favorite days, however, are when Clark comes by to check on her, finding her in the middle of the day, after yet another all nighter of reading Kryptonian non-fiction novels, and he orders her to bed. She doesn't like the orders, but after the first time, she never complained again. Clark had left the Fortress after day three of them being in the Fortress, and came back to check on her a couple days later to find her sleeplessly tired and still reading. After forcing her to lay down, he convinced her to stay put if he taught her one of the lullabies he had learned himself. Now, every night he was with her in the Fortress, they either sung the Kryptonian lullabies together, to each other, or, fell asleep to the voices of their parents singing instead
  * Keeping true to the self-promise, when Marinette returned to Gotham, she excitedly told her family as much as she could
  * Dick, inspired by many of the stories, and wanting to pay tribute to his youngest sister’s heritage, asks if he can create a new hero identity
  * She happily agrees after asking Clark about it over the phone, and Nightwing is born
  * They laugh a bit at it, actually, considering that Robin’s colors are a tribute to the Greysons, and Nightwing is one of the Kryptonian Gods, and yet they've ended up swapped between them
  * Justice League time! This is my favorite part, where it gets into pure identity shenanigans
  * Give it a few more years before the whole idea comes together. Batman may trust his daughter’s brother, but he still needs to get to know him. They still butt heads often enough, but Marinette is a good, if exasperated, mediator that helps them settle down and come to agreements more
  * When the JL is finally founded, Marinette is 25, and Bruce is, in fact, only there for the official first day of it in operation
  * That’s right, Bruce retires! 
  * After so long of fighting the corruption and crime of Gotham, there has actually been progress and improvement. Enough so that Bruce is comfortable with actually retiring as a field vigilante, instead joining the behind-the-scene bats by becoming Agent B
  * Who other than Marinette takes up the cowl of Batman? 
  * She outright told Dick he can't pull off the attitude for it, and even Damian could agree she was the best fit
  * There were, of course, questions of how she would hide the fact of Batman suddenly becoming a woman. After rolling her eyes and saying the fact that female armor doesn't have to look feminine, she tells them that the answer was simple!
  * Stuart Semple
  * That's right, Marinette was already planning to become Batman after her dad!
  * She also manages to convince Bruce to play a long-term prank on the JL, all the way from day one. What is the prank, you ask?
  * They don’t tell anyone except those within the Bat Clan that the cowl is being passed on, and no one will ever know that there was a new identity behind Batman
  * So, how is it pulled off? Like this:
  * For one, Bruce will reveal his identity as Batman as a sign of trust to the heroes of the JL
  * Then, immediately after, he will go home and hang up the cowl for good
  * Then Marinette is going to take out her redesign and take up the Batman role
  * The entirety of the new suit is going to be made with Black 2.0, and combining it with the cloak that will cover her whole body, a new full-face mask/helmet, full body armor, a speed that will keep pictures from getting clear pictures of even her profile, and her Kryptonian ability to masterfully manipulate her voice to keep the frightening baritones of her dad, her identity is securely secret, and the prank perfectly maintainable
  * Add in her own personal touch of changing the usual white eye lenses to gold, layering the cloak with a mechanism that raises and lowers the layers to allow for maximum looming height (where no one can tell if her feet are touching the ground) while also keeping it out of the way when crouching or keeping low, and you have a Batman that not only looks like a literal and legit void with creepy glowing eyes, but one that is going to be scaring the hell out of every single hero, too, when she walks by them in the halls of the JL
  * Really, it’s the perfect functional prank
  * It gets more fun every time she comes home from a mission and tells everyone about how her teammates kept commenting that they had worried about Bruce’s age, but with ‘him’ upping the scare levels and seeming to actually be improving in ‘his’ skills, speed, and strength, they find they have nothing to worry about
  * It’s barely a week in before she overhears a few people considering begging Batman to tone down the endless-void look, but she accidentally scares them off when they spot her, and she’s certain the prank is going to last a good amount of time now
  * Gotham continues to improve, enough so that the constant presence of Batman isn't required, easily manageable by the other bats, even in lessened numbers
  * Most of the bats suspect Marinette taking up the cowl and the new look had a great deal of impact on the most recent crime drops
  * Bruce has taken to putting lawn chairs in the mansion’s library and using one of Marinette’s old sippy-cups for his evening scotch and cocktails, claiming to be catching up on a missed childhood, with an adult twist
  * Bruce discovers the Wii, and family game nights have become a thousand times funnier after all the wrist straps get lost
  * There's something else Gotham and the JL notice after Batman ‘stopped holding back’ along with the new look. Batman got gentle
  * It wasn't that he wasn't gentle before, no; Batman has always cared about others. Has always treated the villains with humanity and made sure the ones that needed it got the treatments they needed, always made sure no one got hurt unjustly and no one died. Always made sure victims were looked after and safe. But now it’s a lot more
  * Batman becomes slower, softer, gentler when handling people, good or bad, ‘his’ fist a gauntlet of iron coated in the fluffiest of velvet and stuffed with plush cotton. He even began using words first a lot more, kicks and fists less and less
  * It boggles everyone this sudden new contrast, this scary as hell void, this renewed cryptid, this beastly monster of the night, having a heart light as a feather, pure as gold
  * In fact, oddly enough, it scares them all, heroes and villains alike, a hell of a lot more
  * Everyone knows never to underestimate someone who seems soft, and if Batman is already a better fighter than before, and softer than ever, then please, they beg in the names of the gods, what else is hidden under that cowl?
  * The prank still works wonderfully, of course, because no one connects the cryptid-ness of the last Robin, that everyone was told had ‘moved on from the Robin mantle’, with the improved cryptid-ness of Batman. Remember that ‘I sure hope it’s just Batman’ thing? Well now they’re frightened of Batman all over again, but they still fear the ‘Return of Robin’, because once again, if Batman has improved, what in the world has Robin been up to?
  * The prank finally ends with the decision of picking her duty over continuing to keep the secret
  * Themyscira is in need of some help, some problem there that the Amazonians can’t figure out themselves
  * Thing is, it’s a women-only place
  * So the decision is to volunteer for the mission, or keep up the prank
  * Obviously, she's a good person and volunteers, deciding it's time for the prank to be revealed
  * Thing is, she doesn’t say she's a woman or even drops the deep scary voice before raising her hand and saying, “I’ll go.”
  * Everyone is dead silent and just stares
  * Her hidden straight poker face cracks and she stands up with a laugh, before she unclasped her cloak and drapes it over the back of her seat
  * Then she pulls off the full-headed mask/hemet, fully breaking the look of an endless void
  * Everything is dead silent still as everyone stares, before Superman drops his head into his hands, realizing what has been happening, and just bemoans, “Kia, why…”
  * That’s when the noise breaks and everyone looks at Superman, basically all asking, “WAIT, you KNOW her???”
  * Marinette is cracking up, trying to suppress her laughter as she subtly sends a message to her family not present at the meeting that the gig is up
  * Everyone quiets down when Batman stands and clamps a hand down on our unmasked Batman
  * “Everyone, this is Marinette, ex-Robin, Bruce Wayne’s daughter, and Kia Jor-El, my twin sister.”
  * It’s noisey all over again, and this time she can't keep the laugh in
  * Diana, though, may or may not be dead silent, staring at Batman, and feeling very, very gay right now
  * Everything settles down eventually, and everything gets back on track, but it will be months before the JL members stop being absolutely disbelieving that they got bamboozled so well and for so long, and they may just be even more frightened of Batman than ever before
  * The Bat Clan gets a whole new round of laughs after Marinette returns from Themyscira and describes the reaction of the Amazons when Diana introduces Batman as one of the volunteering heroes, before remembering to also mention that Batman, despite the name and previous holder of the mantle, is indeed a woman
  * Also, considering that Kryptonians are functionally immortal when their powers are working, Marinette is basically permanently Batman now, and can watch over Gotham and everyone else for basically forever now alongside Superman and Wonder Woman
  * Good luck figuring out how to explain it when the public notices the youngest Wayne daughter isn't aging any more
  * Imagine all the kids she’s probably going to end up adopting into the Wayne family over time, too. ‘Mominette’ is too valid to exclude, and this is absolutely going to be a moment of “Oh my god, it’s a learned behavior.”



**Works inspired by this one:**

  * [Marinette Jor-El Wayne](https://archiveofourown.org/works/24869410) by [CountTashtag](https://archiveofourown.org/users/CountTashtag/pseuds/CountTashtag)




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